The Shawmut Street Extension isn’t much to look at, only a short block in Bay Village bounded on one side by the colorless skin of a concrete parking garage, and on the other by a small, empty lot covered in cracked asphalt.

But 71 years ago on Thursday, the most devastating building fire in New England history occurred here when the Cocoanut Grove nightclub, overcrowded and underprepared, erupted in a suffocating, lightning-fast blaze that killed 492 people.

It’s a tragedy that has been embedded in Boston lore, but one whose exact site remains unknown to nearly all but neighbors and zealous history buffs. That disconnect is about to change, if slightly, when the tiny Shawmut Street Extension is renamed Saturday as Cocoanut Grove Lane.

“Everybody can tell you about it, but nobody can tell you where it was,” said Dr. Ken Marshall, a plastic surgeon whose mother was a Boston City Hospital nurse who tended to victims over four nonstop days. “My mother never recovered emotionally.”

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Mayor Thomas M. Menino is expected to unveil the new street sign at the corner of the extension and Piedmont Street in tiny Bay Village, joined at the 10:30 a.m. ceremony by scores of people with emotional connections to the tragedy — survivors, descendants of the dead, neighbors who have long been aware of this horrific piece of history in their midst.

“It will be closure for me,” said Ann Marie Gallagher, an 87-year-old survivor from Keene, N.H., who plans to attend the ceremony in her first return to the site since the frigid night of the fire. “Whenever this time of year comes, I still have things that hit me. It’s something that never leaves you.”

Gallagher lost her mother and father in the flames, as well as her boyfriend and his parents. They had traveled to Fenway Park from Keene that day for the Boston College-Holy Cross football game, in which Holy Cross stunned undefeated BC, 55-12.

While their parents ate dinner, Gallagher and her high school boyfriend, Fred Sharpy, headed downstairs to dance. Soon, the young couple caught sight of the flames, followed by screaming and pandemonium as an estimated 1,000 patrons ran toward doors that had been locked or were designed to open inward, which became impossible against the crush of people trying to flee.

The fire’s origin remains in question, but a discarded match is believed to have begun the inferno among the many flammable decorations and palm fronds that gave the Cocoanut Grove its tropical theme and helped make the nightclub among the most popular in Boston.

“We saw where the fire was, first off, and Fred said to me, ‘Ann, get on your hands and knees and cover your face,’ ” Gallagher recalled. “That’s the last thing I remember.”

When she woke up, Gallagher was in Massachusetts General Hospital, where the 16-year-old stayed for more than three weeks recovering from respiratory damage caused by toxic chemicals and smoke.

To this day, she has no idea how she escaped.

Ed Murphy, 94, is scheduled to make his first visit to the site. The Holy Cross football captain was heading to the nightclub from the Parker House, where he was staying, when Boston Mayor Maurice Tobin invited him, a teammate, and their dates to a private party upstairs at the hotel.

“We stayed for a while and tried to leave, but they had a big guy at the door who wouldn’t let us out,” said Murphy, who lives in Tewksbury. “Finally, I complained to the mayor, and he said, ‘You don’t need to get out of here. We’ve got a band, we’ve got dancing, we’ve got great food, anything you want.’

‘Whenever this time of year comes, I still have things that hit me. It’s something that never leaves you.’

“He kept us in there the whole night.”

The Cocoanut Grove fire’s origin remains in question, but a discarded match is believed to have begun the inferno among many flammable decorations.

John Rizzo, a 93-year-old from Lynn, plans to travel to Bay Village, too. As a 22-year-old waiter, Rizzo considered himself fortunate in 1942 to have a job at the club, which needed replacements for the staff who had left to serve in World War II.

As flames raced around the Cocoanut Grove, Rizzo fled toward an exit but was forced to a downstairs service bar, where he broke a narrow window and frantically pushed patrons headfirst through the opening and into the night. After helping about 20 people to safety, Rizzo followed suit.

Outside, he looked back and saw a chorus girl in a fur coat sitting by an upstairs window as the fire ravaged the club.

“I yelled, ‘Listen, you’ve got to get out of there. You’ve got to jump,’ ” Rizzo recalled. “As soon as I said that, she jumped right on me.”

Marshall, the plastic surgeon, said the idea to rename the street came over a “good cigar and a cup of coffee” with Mike Hanlon, who worked for Kevin H. White, the former mayor, and is keenly aware of the minutiae of the fire and its aftermath.

“We’re the last generation to have a direct connection with this,” Marshall said. “If we didn’t do anything, nothing would happen.”

The pair also have been helped by Paul Miller, a real estate developer who lives near the site.

“We have a collective history in Boston, regardless of whether you’ve been here six months or 300 years,” Miller said. For that reason, he added, marking a site as important as Cocoanut Grove is appropriate for a city that has always kept its past close.

The renaming, which rarely occurs in Boston, encountered no opposition from the few abutting property owners, Marshall said. On Saturday, the new street sign will join an existing historical marker and a plaque in the red-brick sidewalk.

That plaque, dedicated in 1993 and crafted by a former busboy who survived, describes the site as “Phoenix out of the ashes” — a reference to the many improvements in fire regulations, both locally and nationally, that followed the blaze.

Suzanne Kreiter/Globe staff

John Rizzo, a 93-year-old Lynn man, considered himself fortunate to have a job as a waiter at the club in 1942. As the fire raged, he broke a window and hepled about 20 people to safety.

Christopher O’Neil of Dartmouth and his extended family also are trying to create something positive from the long-ago fire. O’Neil lost two of his grandparents to the blaze, which meant that their three children, including his father, were split up and raised in two new households.

The O’Neil family has launched a foundation to raise money for the families of pediatric burn patients to offset travel expenses incurred during weeks and months of treatment. The foundation has given the Shriners an initial gift of $10,000.

“We’re trying to alleviate the second tragedy, which, in our minds and in our situation, occurs with the separation of families,” O’Neil said.

On Saturday, about 30 members of the family are planning to travel to Boston in a rented bus for what is expected to be an emotional ceremony.

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